# Passkey

> A passkey is a credential stored on the device that replaces a password, unlocked with Face ID, a fingerprint or a screen lock. People give only a user name, and nothing typed can be phished.

Page: https://www.appetiteui.com/glossary/passkey. Passkey sign-in on iOS and Android: how it looks and works. Also called Passwordless sign-in, Credential Manager, Biometric sign-in.

## Why it matters

Passwords are what people forget and what leaks. A passkey removes both, and the sign-in becomes one biometric check.

It is a system dialog, so the design owns the screens around it: the offer, the wording of the button and the fallback.

## iOS and Android

|  | iOS | Android (Material 3) | Appetite UI |
| --- | --- | --- | --- |
| Name | Passkeys, sign in with Face ID or Touch ID | Credential Manager with passkeys | Passkey |
| Flows in the file | Create, Sign In, Cross-Device, Security Key | Same flows, drawn as the iOS dialog | See below |
| Platform support | Preferred by Apple when Sign in with Apple is not used | Android 9 (API level 28) and higher | See below |

## In Appetite UI

Passkey is a dialog set on the Alert page: four flows, Create, Sign In, Cross-Device and Security Key, each in three states, Prompt, Verifying with a Face ID glyph, and Success. It shares the Alert card, a primary action in the tint and secondary actions on flat capsules.

## Example

After a person creates an account, a Create dialog offers to save a passkey. Next time the Sign In dialog asks for Face ID and the app opens without a password field.

## Common mistakes

- Titling a button Sign In when it means Sign In with Face ID. Name the method.
- Mentioning Face ID on a device that does not have it.
- Removing the password fallback before people have passkeys.
- An in-app setting for biometrics, which people already set in the system.

## Questions

### What is a passkey?

A credential stored on the device that replaces a password. People confirm with a biometric or screen lock, and it uses public-key cryptography, so a breach of the service does not expose it.

### Do passkeys work across iOS and Android?

Yes. Android Developers lists support for Android, Windows, macOS and iOS, and several browsers, with passkeys on Android 9 and higher.

## Sources

1. [Apple Human Interface Guidelines: Managing accounts](https://developer.apple.com/design/human-interface-guidelines/managing-accounts)
2. [Android Developers: Passkeys](https://developer.android.com/identity/passkeys)

## Related

- Docs: [iOS](https://www.appetiteui.com/docs/ios)
- Docs: [Alert](https://www.appetiteui.com/docs/alert)
- Glossary: [Sign-in screen](https://www.appetiteui.com/glossary/sign-in-screen)
- Glossary: [Alert dialog](https://www.appetiteui.com/glossary/alert-dialog)
- Glossary: [Permission request](https://www.appetiteui.com/glossary/permission-request)